20 THE BOOK OF THE PEACH. 



of work, the boilers being arranged so that one or 

 both could be worked together, according to cir- 

 cumstances, to heat the 4000 feet of 4-inch pipe 

 attached thereto. I may add that the measure- 

 ments of the hot-water pipes refer to the inside 

 diameters of same. It is important in setting boilers 

 in position on a solid bed of brickwork or concrete, 

 that a proper rise from front of furnace to back 

 should be allowed in order to secure a good free 

 circulation of hot water from the boiler to the flow 

 pipes, in which also a rise of half an inch should be 

 allowed in each 9 feet length of pipe. Thus a 

 rise of about 2 inches should be provided in fixing 

 the bed for the 4 feet 6 inch boiler; 3 inches for 

 the 6 feet 6 inch size; and 5 inches for the 9 feet 

 6 inch boiler; 8 inches in the 15 feet size; and nearly 

 10 inches in the 19 feet heating apparatus. 



The tubular boilers upright and horizontal 

 according to my experience of them, will last a 

 lifetime, and that a long life too. In saying this 

 I have in my mind's eye two or three upright 

 tubulars which at the present time, are apparently 

 as good and do their work as efficiently as when 

 placed in position forty years ago. In the case of 

 small houses, there are various sizes and shapes of 

 saddle boilers to choose from. 



In heating forcing-houses it is good policy to pro- 

 vide them with a liberal supply of 4-inch pipes. It 



